Mixing chamber for the end of an incinerator rotary kiln



H'. J. cATEs, JR., ET AL 3,489,527

Jan. 13, 1970 MIXING CHAMBER FOR THE END OF AN INCINERATOR ROTARY KILN 2Sheets-Sheet l Original Filed April 8, 1965 Jan. 13, 1970 H. J. GATES,JR., ET AL 3,489,527

MIXING CHAMBER FOR THE END OF AN INCINERATOR ROTARY KILN Original FiledApril 8,

2 Sheets--Sheefl 2 FIG.4

R. G J..R y m S E .m N E B O V M E T m C S VVA G J. R N am HT Y B UnitedStates Patent O 3,489,527 MIXING CHAMBER FOR THE END OF AN IN CINERATORROTARY KILN Henry J. Cates, Jr., De Kalb County, and Tom Rosenberg, EastPoint, Ga. (both of 416 Walton Bldg., Atlanta, Ga. 30303) Originalapplication Apr. 8, 1965, Ser. No. 455,357, now Patent No. 3,317,202,dated May 2, 1967. Divided and this application Oct. 19, 1966, Ser. No.601,256

Int. Cl. F27b 7/36; B01j 6/00 U.S. Cl. 23-277 2 IClaims ABSTRACT F THEDISCLOSURE An arrangement for the discharge end of a rotary kilnemployed in a continuous incineration operation as for example in arefuge incinerator for a city. A hood arch arrangement adjacent thedischarge end of a rotary kiln extends downwardly in front of the kilnto protect the discharge end from the reilective heat which would becreated in the mixing chamber into which the kiln discharges. Anarrangement of an offset wall acts as a baille to cause turbulence ofthe gases as they pass from the rotary kiln. A bridge wall acts as abaille and a delector and directs gases from the end of the rotary kilnback towards the gas flow from the kiln.

This is a division of application Ser. No. 455,357, tiled Apr. 8, 1965,now Patent No. 3,317,202.

CROSS-REFERENCE TO RELATE IT TO APPLICATION AND PATENTS Parentapplication Ser. Nos. 56,015 and 455,357 respectively U.S. Patents Nos.3,212,465 and 3,317,202..

BACKGROUND OF THE INVENTION The lield of the invention including thepatent classification and a description of the prior art includingreferences to specific prior art, where appropriate, may be found fromreading the above noted patents issued from the parent applications ofthis present application.

FIG. l is a vertical cross-sectional view through a typical plant usingthe method and apparatus of the present invention with the air and gasow shown by light lines with arrowheads thereon.

FIG. 2 is a front elevational view of the nose ring casting of therotary kiln.

FIG. 3 is a cross-sectional view of the nose ring casting takensubstantially along lines 3-3 in FIG. 2.

FIG. 4 is a diagrammatic, perspective view of the mixing chamber usedwith the rotary kiln.

FIG. 5 is a cross-sectional diagrammatical view of the mixing chambershown in FIG. 4 in conjunction with a diagram of the end of the rotarykiln.

Referring initially to FIG. l of the drawings for a description of theplant and the operation thereof as a whole and the relationship betweenthe individual elements of the plant as well as the `air flow and hotgas flow therein, it is seen that the refuse 40, which is stored outsidethe plant, is picked up periodically from time to time by means of atraveling crane 42, or by a conveyor system (not shown) or any othersuitable means, and fed in increments into the entrance to the plant 50,through a chute 52 having diverging walls 54, 56 and a bottom which isconnected to a drying chamber designated by number 100. Chamber 100 haspositioned for operation therein a pair of drying grates 102, thedetails of which will be described later on under the heading DryingGrates.

In the following description, various number groups have been assignedto particular elements, to-wit: the

plant itself and component structure are identified in the group between50 and 99, all of the numbers in the group refer to drying grate parts,while the ignition grate chamber and ignition grate structures areidentified in the 200 and 300 group, the rotary kiln and attendantstructure and parts are identified in the 400 group and the mixingchamber and its structure is identilied in the 500 group, except forthat portion of the chamber which is actually a part of the plantstructure and for some parts which may overlap different groups. Theduct work and other connections which are located Ibetween two elementswill carry the group legend depending upon which group it is moreclosely associated with from the standpoint of clarity.

Leading from the incoming chute 52, there is a sand seal joint structureidentified generally as 58, and which will be described later on withparticular emphasis on the details of construction. The refuse 40,dumped through the chute 52, falls into the rst chamber of the plant 50which is a pre-drying chamber 100 having drying grates 102 locatedtherein. Refuse dropped on top of the uppermost drying grate 102 iscontinuously circulated and moved down the stair-step arrangement of thegrates which are reciprocated by a power-driven connection means thatwill |be described later. Following the pattern of FIG. l, it iS seenthat the refuse is carried down the upper and lower drying grates anddropped into the ignition chamber 200 which has the ignition grates 202located therein. For the time being, the details of the grates 202 willnot be discussed and will be covered later on under the particularheading of Ignition Grates.

The upper portion of the ignition chamber 200, represented by thenumeral 204, connects on one side with the drying chamber 100 andconnects to the rotary kiln 400 by a particular seal plate arrangement320. This seal 320 assures an air seal between the ignition grates 200and rotary kiln 400; and has arranged transversely thereacross a ilatbaille arch 206. In the pre-drying period, the refuse is pre-driedbeneath the feed chute as it is moved slowly by means of the movablegrates 102 toward the second or iginition chamber 202. The movablegrates 102 of the drying chamber 100 alternate between stationarygrates, as will be apparent hereinafter, and the arrangement includestwo continually moving and reciprocating grate sections mounted on aslight angle with the horizontal to provide a downward movement and tocause a tumbling action which gives the advantage of exposing all refusesurface to hot gases for pre-drying. In FIG. 1, as pointed outhereinbefore, the light lines with `arrowheads thereon and the indiciaa, represent generally the ilow of air and gases throughout the plant,and it is noted that the hot gases and air which flow from above theignition grates 202 'are directed back somewhat into the pre-dryingchamber 100 above the pre-drying grates 102, thereby aiding the dryingof the refuse passing thereacross. The movement of these gases and thisair from the ignition grates 102 is aided measurably by the presence ofthe baille arch 206 located above the ignition grates 202.

In conjunction with the ignition grates 202, in order to provide airwhich is necessary for good combustion of the refuse, there is suitableduct work 20'4 extending vertically in the building space below thedrying grates 102 and attached to the upper end of the ignition grates202 drawing primary air through a blower 210 and passing it by forcethrough the duct work 204 into the sides and beneath the ignition grates202, as will be more apparent hereinafter. It is this air from the ductwork 204 which passes under, then up through the ignition grates 202 andbed of refuse and across the ignition grates 202 thus mixing with thegases produced thereat and rising above the bed of refuse. Additionalair is taken oil from the duct system and released over the burning bedof refuse by the over fired air system 205 on both sides of the chamber202 involving a particular arrangement of ignition assembly which willbe described later on. The refuse is moved along the ignition chamber byuse of the movable grate sections, which alternate between stationarygrate sections. The duct system 205 provides air over the refuse bed.The duct system is located on both sides of chamber 200 and the air ilowis controlled by dampers.

The baille arch 206 is constructed from suitable lire brick andstructural material over the ignition grate chamber and serves as adeiiector to direct the hot gases over the bed of refuse on the dryinggrate.

The gases are then directed across the top of the baille 206 and througha structural passageway 60 formed in the building structure into thechamber 500 to be described later on. Some gases from beneath the baille206 pass up through a small passageway 62 and join in the chamberpassageway 60 with the gases passing therethrough. As the refuse passesacross the ignition grates 202, the grates are protected by a specialconstruction of the sidewall castings to protect the side walls 212 ofthe ignition chamber 200 from the burning of the refuse. In addition,the side wall castings 212 are protected from the heat of the chamber bythe forced draft air that passes back of them and cools the castings.The particular supports for the grates and the operation thereof,including a rocker arm method or a wear shoe method, will be describedlater.

From the ignition grates 202, whereon the refuse is constantly agitatedand turned downwardly, the burned material is dropped into the rotarykiln 400 for the remainder of the burning operation. Kiln 400 isconnected to the chamber 200600 and driven by a particular geararrangement 402 which will be described in detail in conjunction with adescription of the rotary kiln parts and it will suffice for the presentto say that the kiln is rotating constantly and is supplied with burnedmaterial from the ignition grates 202 and with a quantity of hot gasesand air a entering the kiln directly from the surface of the bed of theburning refuse. The remainder of the burning of the refuse takes placewithin the kiln 300 and the discharge end of the ignition chamber isprotected from the heat by castable refractory mounted on a dischargecasting arrangement, the details of which will appear later. The hotgases that result from the burning of refuse in the ignition chamber 200are utilized for pre-drying of the refuse in the drying chamber and areodorless in character. To remove the odor from these gases, they aredirected over the rotary kiln by the by-pass duct 60 which spills thegases into the chamber 500 following the rotary kiln discharge end. Thischamber 500 mixes the gases at a suilicient temperature to remove theodor from the hot gases. The mixing chamber 500 is so designed to causeturbulence by means of the bridge wall 1506 within the chamber 500 andthe offset wall 504 of the chamber according to a more detaileddescription to follow. The refuse, as it is received by the rotary kiln`400, is tumbled to expose all surfaces of the refuse to the hot gasesand to complete the burning of the refuse. The rotary kiln is driven bya main drive gear which meshes with a girth gear mounted around therotary kiln. The ash, as it is discharged from the end of the rotarykiln 400, is dumped into the diversion gate housing 502 which drops ashonto a diversion gate 508 and into one of several residue conveyors.When properly installed and operated, the incinerator unit or plantshall be capable of operating entirely satisfactorily without manualstoking and shall produce a line, completely consumed residue or ash.

ROTARY KILN According to the previous description of the method andapparatus, the rotary kiln 400 receives the burned refuse from theincinerator ignition grates 202 and com. pletes the combustion of thismaterial, reducing it to a line ash. Kiln 400 is an elongated,cylindrical affair which is supported for rotation about its centrallongitudinal axis by means of supports 402, 404 attached to a rotarykiln support independent of the building structure and rotatablysupporting the shell 406 of the kiln 400. In addition, a particular'typeof support and seal 408 supports the outer or discharge end of the kilnwhile another arrangement of seal and girth gear support 410 supportsthe entrance end of the kiln 400 and retains said kiln 400 and shell`406 in communication with the discharge casting 230 on the ignitiongrates to receive the burned refuse therefrom.

The special mounting feature of the girth gear and seal arrangement 410is particularly noteworthy and will be described now in detail. Theshell 406 of the kiln 400 has surrounding it and arranged in concentricalignment, an outer girth gear 412, having teeth 414 about the peripherythereof and receiving from a power driven drive gear (not shown) acontinuous gear driving relationship which is designed to turn thecylindrical, rotary kiln 400. Because of the heat generated inside ofthe rotary kiln 400, the steel shell 406 has the tendency to expand andcontract. To keep a constant, even meshing of the drive gear and girthgear 412, it becomes important to employ some method of compensating forthe fluctuation of the kiln shell 406.

A plurality of spring plate mounting assemblies 418 are attached withone end 420 thereof to the shell of the kiln 406 and having the otherend thereof, 422, pivotally attached by a pin 424 to a position insideof the girth gear 412. Reference to FIG. 1 discloses that each of theassemblies 418 consist of an elongated bar or strap member 426 havingone end thereof Welded to a bracket assembly 428 having the pivot pin424 attached therein. The other end of the bar 426 is welded to theshell of the kiln 406 at a diagonal position from the position of pin424 on the girth gear 412. The girth gear 412 drives the kiln 400through the connection made by the pivotal attachment of the bar 426from its position on the inside of girth gear 412 to its welded positionon the shell of the kiln 406. However, when the shell 406 expands orcontracts, the expansion and contraction is of no serious consequence,since it is, in effect, absorbed or compensated by an equal movement ofthe bars 426 about their respective pins 424. This eliminates orsubstantially reduces the warping and destruction of the shell `406 fromthe changes in temperature.

The discharge end at 408 of the kiln employs a particular advantageousarrangement of discharge castings 432 protecting the end of kiln 400 inthe opening in the wall through which the kiln discharge the ash andburned residue.

The terminal end 434 of the kiln 400 is provided with a plurality of thenose ring castings 434 arranged in radial relationship and forming acomplete closed circle on the end of the kiln. Each of the castings 432is independent of the other and may be removed from the kiln byunscrewing a bolt assembly `436 which retains the individual nose ringcastings 432 in place on the end of the kiln 406.

MIXING CHAMBER The mixing chamber shown in FIGS. 4 and 5 is representedgenerally by the number group 500 and as is seen in FIG. 1, the mixingchamber assembly 500 receives the residue and ash from the end of therotary kiln 400. FIGS. 4 and 5 are diagrammatic views in reduced size inorder to show the particular relationship of the mixing chamber and inconjunction with the end of the rotary kiln 400. A hood arch arrangement503 extends from an attached position above the end of the rotary kiln400' and downwardly in front of the kiln 400 to protect the dischargeend castings 432 of the rotary kiln from the reflected heat of themixing chamber S00. The particular arrangement of the offset wall 504acts as a bamle to cause turbulence of the gases as they pass out of therotary kiln 400. A bridge wall 506 acts as a baille and deflector and asa deector, it directs gases from the end of the rotary kiln 400 backtoward the gas flow from the rotary kiln, thereby aiding in producingturbulence in the mixing chamber. Proper turbulence within the mixingchamber is essential for proper mixing of the combustion and bypassgases and for complete combustion.

A plate seal 510, part of the mixing chamber that encases the outlet endof the rotary kiln 400, employs the unique feature of a small gap 512 inthe circular plate seal 510 which allows cool air to be let in aroundthe discharge castings and in conjunction with the particular shape ofthe hood arch 503 aids in protecting these castings from extensive heat.

The siftings hopper 600, located under the drying grates 102, asmentioned in connection with the ignition grates 200, comprises anopen-top, elongated hopper 602 with a closed bottom. A power drivenscrew conveyor 606 conveys the droppings and siftings from the dryinggrates 100 onto the top and rear of the ignition grates 200.

A water seal chamber 700 beneath the ignition grates 200 is filled withwater to the approximate water line shown in FIG. l. It has submergedtherein the entrance end of a long trough having a long screw conveyortherein. The purpose of this is to collect small hot ash that fallsthrough the ignition grates stringers 240, 242 and to quench the ash asit falls into the screw conveyor 706 by which it is conveyed to thediversion gate housing 508 at which point it falls into residueconveyors (not shown). The water seal in chamber 700 maintains the airthat is under the grates 200 coming from the force draft duct system inthe ducts 226 and 228. The hopper eliminates manual collection of theash and constantly reinjects the ash1 into burning process.

We claim:

1. In an incinerator mixing chamber having one end of a rotary kilnextending therein and which kiln has an arcuate terminal edge around akiln opening therein, said kiln dumping burned material from the bottomdischarge thereof, and there being radiant heat generated within saidmixing chamber which could adversely atfect the end of said kiln,

(a) a plate seal encasing the end of said kiln next to said mixingchamber to help seal same from said mixing chamber and said plate sealbeing slightly spaced from said kiln and having a small gap thereinpermitting air to circulate and to help cool the discharge end of saidkiln, and

(b) a refractory hood arch in said mixing chamber spaced from said kiln,said hood arch extending about said arcuate terminal kiln edge exceptfor the lower discharge portion thereof from which said burned materialis discharged and said hood arch protecting the discharge end of saidrotary kiln from the radiant heat which is generated within the mixingchamber.

2. The mixing chamber in claim 2: a bridge Wall sloping and extending atan angle from beyond the discharge end of said kiln and providing a bafewhich deflects and directs gas from the direct end of the rotary kilnback towards the gas ow from the rotary kiln.

References Cited UNITED STATES PATENTS 2,269,273 1/1942 Krogh et al110-8 3,042,389 7/ 1962 Gieskieng 263-32 JAMES H. TAYMAN, JR., PrimaryExaminer U.S. C1. X.R.

23-279; llO-S, 14; 263-46, 22(l 32, 285--134

